The present invention refers to a build-in linear emitter for irrigation, which is inserted and welded into the interior of a drip irrigation pipe during its production phase, allowing a subsequent cutting-off of a specific part followed by an automatic perforation of the drip irrigation pipe for the creation of outlet openings for the water, as well as a method for inserting and incorporating the emitter into the irrigation pipe.
The drip irrigation pipes with build-in emitters are a complex product and constitute the most important element of drip irrigation. The reliability of their function as well as their production cost, characterize the quality, cost, and agricultural development in its entirety.
The investment cost for the production lines of drip irrigation pipes is also substantial. Of particular importance is the cost of the sophisticated mechanism for orienting, inserting and detection of the emitters, as well as for the perforation of the irrigation pipes, exactly at the area of a necessarily wide basin for the outlet and for the final collection of the water at the end of the paths in the interior of the emitter, in order for the water to be discharged on the soil.
The size of the problem will be understood, if we consider that the emitters are inserted at a speed and frequency of over 1000 emitters per minute. Hence, the production of up-to-date drip irrigation pipes is an exclusive privilege of financially strong companies and the cost of the end product is substantially incurred by the cost of the sophisticated investment.
There are several known systems for insertion and incorporation of common emitters, wherein their position, and in particular that of the wide outlet basin, should then be detected and the drip irrigation pipes should be perforated. Exemplarily, EP 0 970 602, EP 1006778, WO 99/62691 are mentioned.
Other patents, such as EP 1 541 014 A1, US 2007/194149 A1, also provide the known wide water outlet basins, with special protrusions from the bottom of the basins, the protrusions having a significant height. The tip of the protrusion along with a part of the pipe covering them is cut off in a subsequent stage, thus forming the water outlet openings. The problems presented in the above-mentioned technologies are both due to the insertion method and to the emitters themselves.
In particular, in EP 1541 014 A1, as a result of the unified and uniform concave shape/profile of the tread, the elastic material of the wheel will be locally compressed and withdrawn at a greater extent in the area of the protrusions, a cavity will be formed there which will have the shape of a concave surface of a frustum cone or a frustum pyramid with a very extended base surface in relation to its height. The same concave shape will be adopted by the warm pipe under configuration due to the negative pressure in the cooling bath, with the result that the system will not work, for two reasons: a) the dimensions of the base of the hollow pyramid of the swelling around and above the water outlet basin of the emitter should exceed the limited width of the emitter itself, and b) due to the vacuum in the cooling bath, the swollen material will tend to detach, preventing the pipe from welding on the sides of the emitter protrusions.
Similar problems appear in US 2007/194149 A1: For example, this patent employs a conventional wide water outlet basin with the known common problems in this art, e.g. the reduction in water flow velocity with a subsequent inefficient washing thereof, the presence of impurities and a gradual clogging of the water paths, which constitutes the major problem of the drip irrigation. In particular, a high protrusion is raised above the bottom of the outlet basin, however without providing a base of the protrusion at the height of the outer solid and full cylindrical surface by which the emitter is welded on the pipe, and without right and left transverse bars which ensure the welding of the swollen part of the pipe directly on the protrusion, such that the welding and finally the cutting-off is facilitated. The swollen pipe remains suspended and free around the protrusion, being welding only on the protrusion tip.
Also the technology of WO 92/05689 regards self-adjustable emitters having an irregular and intensely convex, non-cylindrical shape, which are inserted and welded in the interior of the pipe, swelling the whole pipe locally. These have a cannula also covered by the walls of the pipe, which will be cut off in a subsequent phase by a rotating cutting device, thus forming a water outlet to the ground. The disadvantages of this technology is the fact that again there is one and only water outlet, through the above mentioned cannula, which directly communicates with the sensitive self-adjustment chamber of the water supply inside the emitter, which increases the susceptibility and delicacy of the system to the random inflow of foreign matter (debris) from the ground and not from the water itself, as in the previous cases, since the single end of the cannula lies on the soil. Another disadvantage is the fact that for the welding of the emitter, the pipe is swollen locally and intensely in a wide area beyond the protrusion area, and the thickness of its walls becomes peripherally smaller over the entire cross-section. The pipe becomes thinner not only over the part that is occupied by the emitter but also over the whole free cross-section, resulting to a reduction in the pipe strength to internal functional high hydraulic pressures. In addition, to produce such a sophisticated pipe with extreme large and intensive swollen areas, that cannot be calibrated, is not at all an easy task. Furthermore the surface of the end product is rough and due to the lack of calibration, with non equal outer diameter and wall thickness even between the swollen areas (emitters).
US 2006/186228 discloses a dripper adapted to be bonded to interior of an irrigation pipe during manufacture and to be associated with an outlet opening in said pipe. The dripper comprises an outwardly facing surface adapted for the bonding, an outlet area associated with the surface, and at least one bulge near the outlet area. The bulge defines an outermost portion of the surface at least during manufacture of the pipe, and is adapted to form, when the dripper is bonded to the pipe, a raised outlet region in the pipe associated with the bulge. The bulge and outlet area are designed so as to form the raised outlet region suitable for at least a part of the outlet opening to be formed therein and be defined by the material of the pipe.
EP 1 541 013 disclose s a droplet former, designed to located at intervals to the inside of an irrigation pipe to control the flow of water through its outlets, which consists of a plastic bar with a water collection chamber fed by a passage and a labyrinth channel. The bar is attached to the inner surface of the irrigation pipe, especially by welding, that the collection chamber is aligned with a pipe outlet. The collection chamber has a central projection that lifts the wall of the irrigation pipe from the inside so that it can be trimmed to make an outlet with its edges in contact with the projection to form a valve.
Regarding the cutting devices described in the EP 1 541 014 A1 wherein the fraise bears a simple cylindrical profile and the pipe is flattened only by stretching it on a big dram. The disadvantages are the following: a) the pipe neither can be nor remain exactly flattened especially at both ends of the closed flattened profile of the pipe due to the fact that it is not continuously pressed from both sides, b) the flattened pipe could move sideways (left and right) on the dram causing problems by the cutting process c) the cylindrical profile of the fraise is not the best design since the pipe itself could be damaged from the fraise at areas it should not, especially at both ends (that are not pressed) of the closed flattened profile of the pipe which could emerge over the short protrusions (especially by thick wall pipes).